1. Technical Field
This invention relates to studded footwear such as sports shoes, for example football boots track and field shoes, golf shoes, and footwear for other sports. The term xe2x80x9cfootballxe2x80x9d is intended to encompass all sports known as football, such as soccer, rugby and American and Australian football.
2. Discussion of Known Art
The studs of the present invention are intended to provide traction, having a ground-engaging part of a type suited to the sport involved. Thus, studs for football tend to have relatively sharp ground-piercing spikes, while those for golf shoes currently have several relatively soft and blunt ground-gripping or turf-engaging cleats. The studs are detachably fastened to the sole of the article of footwear, by a screw-threaded spigot on the stud engaging in a correspondingly threaded socket in a receptacle melded in, or otherwise secured to, the shoe sole.
The screw-threaded connection must be designed to ensure that the stud remains in place, even when high torque or traction forces are applied, and in particular that the stud does not unscrew accidentally. Known studs have either a single start thread or a multi-start thread. A single start thread is the simplest thread form and provides a greater resistance to unscrewing than a multi-start thread. It also provides a strong connection over the several turns of the thread on the spigot and socket. However, because of the number of turns needed to attach and detach the stud, removal and replacement with a single start thread becomes a time-consuming operation. A multi-start thread has a steeper helix angle, which enables a spigot of any given length to be inserted into the socket with less rotation. Also, because a multi-start thread is deeper cut than a single start thread, the shear strength of the thread is greater, so that a shorter spigot can be used.
Whether a single start or multi-start thread is used, the studs and sockets also typically incorporate a locking ratchet to prevent accidental unscrewing of the studs. Typically, the stud and socket each have a set of teeth which inter-engage as the stud is inserted into the socket. The arrangement of the teeth allows the stud to be in any one of a number of positions relative to the socket when it is fully inserted.
The screw threads and locking ratchets described are quite adequate where the final rotational orientation of the stud relative to the sole is not significant. In fact, currently most studs are circular or otherwise rotationally symmetrical, and their final rotational or angular orientation relative to the shoe sole is not relevant.
However, in some sports where the forces on the studs are relatively high and of a particular type, such as lateral forces or forces due to rapid forward acceleration of the wearer of the shoe, studs which are specifically oriented can be more effective. (The term xe2x80x9cspecifically-oriented studxe2x80x9d will be used herein to include studs which are non-rotationally symmetrical, or studs which are rotationally symmetrical but whose final orientation relative to the shoe sole is significant.) A specifically-oriented stud must be oriented very precisely relative to the shoe sole to ensure that it functions in the desired manner. The known screw-threads and locking ratchets are unable to provide this precise orientation. For example, although a single start thread orients the stud at the start of its insertion, the multiple turns and the locking ratchet mean that its final position cannot be predicted. A multi-start thread of course provides a plurality of starting positions, and the locking ratchet a plurality of end positions.
The present invention aims to ensure that a stud can be precisely oriented relative to its socket and receptacle; orientation of the receptacle relative to the shoe sole is of course necessary, but does not form part of this invention.
According to a first aspect of the present invention, in a combination of a shoe stud and receptacle, the shoe stud includes a ground-engaging part; the two components are adapted to be secured together by a multi-start threaded connection comprising a screw-threaded spigot on one of the two components adapted to be inserted with rotation into a screw-threaded socket on the other component. A locking means for the components is arranged to become inter-engaged at least when the spigot is fully inserted into the socket to resist unscrewing of the assembly. The stud and receptacle have means to determine the initial position of the stud relative to the receptacle, and means to determine the final position of the stud relative to the receptacle.
Thus, the initial angular orientation and the final orientation of the stud relative to the receptacle are both determined. A stud can therefore be specifically oriented relative to the receptacle, and hence to the shoe sole.
The multi-start thread may have two, three or more starts, to reduce the number of turns required to attach and detach the stud. In one embodiment the thread is a three-start thread, and in another embodiment it is a six-start thread. This enables the stud to be attached in half a turn, which makes removal and attachment easy.
The means to determine the initial position of the stud relative to the receptacle may be provided by the threaded connection, with one of the threads and grooves being different from the other or others to provide a key and complementary keyway.
The key may comprise an enlarged thread on one of the components and a correspondingly enlarged groove on the other component. The thread and groove are preferably enlarged radially. The enlarged thread will only fit in the enlarged groove, thus determining the initial position. The strength of the threaded connection is not affected significantly by this.
Alternatively, the key comprises a bridged thread on one of the components, and a removed thread on the other component. Thus, on the one component the space between the crests of two adjacent threads is filled in, and on the other component the thread between two adjacent roots is removed. This provides the necessary initial orientation of the stud relative to the socket, while not affecting the strength of the threaded connection significantly.
Conveniently the key is provided on the receptacle and the keyway on the stud. Alternatively the key could be on the stud and the keyway on the receptacle.
The locking means preferably comprises radially facing locking formations on the stud and receptacle operative to come into mutual engagement when the spigot has been screwed into the socket to a predetermined axial position. One of the locking formations comprises at least one radial projection, while the other comprises at least a radially-facing lead-in ramp, recess and stop means. The projection rides over a lead-in ramp before snapping into a recess, and then engages the stop means to prevent the stud from being screwed any further into the socket. The locking means allows the stud to be unscrewed in response to application of a predetermined torque by resilient yielding of the locking formations. This locking means has the advantage of providing a tactile and audible indication of locking, as the projection makes a click which may be felt and/or heard as it snaps into the recess. This locking means also adds to the strength of the connection between the stud and the receptacle. Preferably two locking formations are provided, but it would be possible to provide four or more.
Where the stud is attached in half a turn and two locking formations are provided, the locking formations may be on different diameters. This helps to provide a positive initial orientation of the stud and ensures that no cross-threading can occur.
The projections are on different diameters, while the ramps, recesses and stop means are formed on the walls of annular channels of corresponding diameters.
Alternatively, the locking means may comprise locking formations as a ring of posts extending axially from one of the components and a ring of radially projecting teeth on the other component, arranged such that when the spigot has been screwed into the socket to a predetermined axial position, engagement of the teeth with the posts causes resilient deflection of the posts, and engagement of the teeth between the posts causes inter-engagement of the locking means.
With either type of locking means it is easy to arrange the locking formations circumferentially relative to the key and keyway to ensure the precise final orientation of the stud relative to the receptacle. The stud may therefore be a specifically-oriented stud, and in particular a non-rotationally symmetrical stud.
The method of orienting the stud relative to the receptacle may also form part of the invention. A second aspect of the invention relates specifically to a shoe stud.
According to a second aspect of the invention, a stud, for use with an article of studded footwear having a receptacle with a multi-start screw-threaded socket, has a spigot with a multi-start screw thread complementary to the screw thread of the socket, such that rotary insertion of the spigot into the socket secures the stud in the socket. The spigot includes one component of a helical key and complementary keyway, of which the other component is provided on the receptacle, the helical key and keyway defining the position of the spigot relative to the receptacle at the start of the insertion of the spigot into the socket.
Preferably the keyway is provided on the spigot, but it may instead be provided on the receptacle.
The keyway preferably comprises a groove of the screw-thread on the spigot which is of different dimensions from the other or others. For example, the groove may comprise an enlarged groove; that is, the groove may be enlarged radially or by the removal of a thread.
The stud may also include one component of a locking means, of which a complementary component is provided on the receptacle to receive the stud in the socket. The stud may be a specifically-oriented stud, and in particular a non-rotationally symmetrical stud.
A third aspect of the invention relates to a receptacle for incorporation in an article of studded footwear, the receptacle being adapted to receive a stud.
According to a third aspect of the invention, a receptacle for incorporation in an article of studded footwear has a multi-start screw-threaded socket adapted to receive a spigot of a shoe stud. The spigot has a multi-start screw thread complementary to the screw thread of the socket, such that rotary insertion of the spigot into the socket secures the stud in the receptacle. The receptacle has one component of a helical key and complementary keyway of which the other component is provided on the spigot, the helical key and keyway defining the position of the spigot relative to the receptacle at the start of the insertion of the spigot into the socket.
Preferably the key is provided on the receptacle, but it may instead be provided on the spigot.
The keyway preferably comprises a thread of the screw-thread on the socket which is of different dimensions from the other or others. The thread may comprise an enlarged thread which may be enlarged radially or formed by a bridged thread.
The receptacle may also have one component of a locking means, of which a complementary component is provided on the stud.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following definitions, descriptions and descriptive figures of specific embodiments thereof wherein like reference numerals in the various figures are utilized to designate like components. While these descriptions go into specific details of the invention, it should be understood that variations may and do exist and would be apparent to those skilled in the art based on the descriptions herein.